Objective: Popular gonad shield designs aim to provide coverage of the true pelvis, which is presumed to be the probable location of the ovaries. Shields are frequently placed inaccurately, especially in children, obscuring important orthopaedic landmarks on pelvic radiographs. We aimed to identify the position of the ovaries and asses how this may vary with age and the degree of bladder filling. We aimed to identify the position of the ovaries and asses how this may vary with age and the degree of bladder filling.
Methods: Using MRI examinations of the pelvis in women and children, we located 594 ovaries in 306 female patients aged from birth to 59 years.
Results: This study provides new evidence that bladder filling affects ovary position. A lower than expected number of patients had both ovaries within the pelvis if the bladder contained more than a moderate volume of urine. Bladder emptying should be achieved wherever practical if a shield is used. In children under the age of 7 years, more than half (19/37) had at least one ovary outside the true pelvis. There was a significant association between age and ovary position, with the percentage of patients with one or both ovaries outside the true pelvis decreasing with age (χ(2), p<0.0001).
Conclusion: The embryological descent of the ovaries into the pelvis would appear to continue after birth, well into childhood. Current popular shield designs are therefore inappropriate for use in young children. Given the high risk of obscuring critical landmarks, coupled with the new evidence that even accurate placement will not necessarily protect the ovaries, the use of pelvic shields in girls should be reconsidered.